Strand scission of DNA caused by bleomycin A2 (BLM-A2) and binding of the antibiotic to DNA was studied in vitro, examining the results of sucrose density gradient centrifugation and Sephadex G100 column chromatography. BLM-A2 caused strand scission of both single and double stranded DNA of E. coli or HeLa cells at the concentration of 1.6 μg/ml, but not that of ribosomal and transfer RNAs, in the presence of 1 mM 2-mercaptoethanol. When 2-mercaptoethanol was omitted, no strand scission was observed. The action of the antibiotic was inhibited by addition of 0.1mM Cu++, Co++, Zn++, and 1mM ETDA. By dialysis of the reaction mixture, after the incubation, double stranded DNA treated with BLM-A2 was partly converted to single strand and strand scission was more markedly demonstrated. Binding of 3H-BLM-A2 to DNA was observed regardless of the presence or absence of 2-mercaptoethanol and amounts of bound BLM-A2 to single stranded DNA was about twice higher than to the double stranded. Addition of Cu++, Zn++, EDTA, or phleomycin inhibited binding of BLM-A2 to DNA but that of actinomycin, mitomycin or pluramycin did not show any effect.
This paper concerns the relationship between the extent of serum-protein binding of antibiotics and the corresponding effluent volume (Ve), and the relationship between the protein-binding extent and the gel-affinity. In the study of the former relationship, the Ve values of penicillins and other antibiotics were estimated by gel nitration. Compounds showing an increase in serum binding also showed an increase in the Ve value. Accordingly, the extent of binding to serum proteins could be predicted without using serum. In studying the latter, the batchwise method was used, by which, a similar relationship between the extent of protein binding and the corresponding gelaffinity was elucidated.
The stereoisomer (trans-isomer) of benzylpenicillin was examined for its antibacterial activity and properties as a substrate and inducer of β-lactamases in comparison with benzylpenicillin. The minimum inhibitory concentrations of the trans-isomer against Staphylococcus aureus FDA 209P and Bacillus subtilis PCI 219 were 1.6 and 12.5 μg/ml, respectively, which were about twenty-five times higher than those of benzylpenicillin. However, the transisomer was very stable to the penicillinases prepared from both S. aureus and Escherichia coli carrying an ampicillin-resistant R factor. The rates of hydrolysis of the trans-isomer by these pencillinases were less than 3 % of the corresponding rates with benzylpenicillin as a substrate. The trans-isomer was a powerful inducer of the penicillinase synthesis by S. aureus and of the cephalosporinase synthesis by Proteus vulgaris.
A new antibiotic, named aranoflavin, which inhibits growth of bacteria, protozoa, and tumor cells in vivo, has been isolated from Arachniotus flavoluteus. The antibiotic was separated into related two components designated as aranoflavin A (C23H33NO6), and aranoflavin B (C26H39NO9).
A series of new antibiotics was derived from coumermycin Ax by reaction with 4-acetoxy-3-aryl and 3-aralkyl benzoyl chlorides. The compounds with a 3-benzyl-4-hydroxybenzamido or a 3-β-phenylethyl-4-hydroxybenzamido side chain inhibited Gram-positive bacteria at very low concentrations in vitro, protected mice against infection, and gave satisfactory blood levels in dogs on oral dosing.
Janiemycin is a new basic peptide antibiotic produced by a strain of Streptomyces macrosporeus ATCC 21, 388. It is a bactericidal compound, active primarily against gram-positive bacteria. In model murine infections with Streptococcus pyogenes C203 and Diplococcus pneumoniae Type 3, janiemycin is as active as penicillin G; moreover, a single subcutaneous dose provides prolonged protection (at least 48 hours) to mice infected with S. pyogenes C 203. Janiemycin and enduracidin are apparently related, but they are easily distinguished by the absence of α-amino-3, 5-dichloro-4-hydroxyphenylacetic acid from the hydrolysate of janiemycin.